DESCRIPTION (from applicant's abstract): The applicant proposes studies to evaluate the hypothesis that HIV infection leads to destruction or dysfunction of the bone marrow microenvironment such that multilineage hematopoiesis is altered. The Investigator has developed a human bone marrow microaggregate culture system that supports multi-lineage and lineage committed hematopoiesis in vitro for up to 8 days, and is permissive for HIV infection. Results from experiments assessing the effects of HIV infection in this system will be compared to data obtained from the evaluation of bone marrow from HIV infected individuals, and also correlated with evaluation of bone marrow cell proliferation and turnover in HIV and normal subjects, using the introduction of deuterated glucose. The Investigator will use these studies to determine if HIV infection suppresses multilineage hematopoiesis by inhibiting proliferation, differentiation or survival of hematopoietic progenitor cells, and will also investigate potential mechanisms for this inhibition, including alteration of cytokines or disruption of surface interactions.